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If you run a food business, chances are you’ve had to freeze food at some point or another. Freezing is a fantastic way to stop the spread of dangerous microbes as well as ensuring that food retains its nutrients. However, just because food has been frozen, doesn’t mean it’s totally safe to eat. Let’s look at some of the finer points of freezing food.

How does freezing protect food?

Unbeknownst to many, freezing does not actually destroy bacteria in food. Instead, it reduces the activity levels of bacteria to near zero and stops them reproducing to harmful levels. Freezing also slows down the oxidisation process caused by enzymes in food, making it last much longer. However, it’s important to remember that bacteria in food will multiply rapidly as soon as it starts to thaw out.

What foods can I freeze?

Most foods can be frozen and defrosted without issue. However, foods that contain a large amount of water will spoil either in the freezer or after defrosting. Foods that shouldn’t be frozen include eggs, watery greens (lettuce, cucumber, celery), herbs, creamy sauces, and soft cheeses.

How long can I freeze food?

Due to the ongoing oxidisation of enzymes, frozen food will continue to spoil when left in the freezer for long periods, albeit much more slowly. For this reason, it’s important to know the maximum freezing lengths for different types of food.

When freezing food for long periods, it’s a good idea to label food with your own ‘use by’ date before putting it in the freezer. This way, you’ll always know whether food buried at the bottom of your freezer is still good to serve. The FSA suggests that food can be frozen up until its use by date. For more general guidance, you can look at the US guidelines on freezing times.

Can I cook from frozen?

The FSA recommends that you fully defrost all food before cooking. This is because frozen food takes a lot longer to cook through; you may find that the outside of the food burns before the inside is cooked. However, if you have a way of ensuring a safe internal temperature of your food (e.g. by using a meat thermometer) then cooking from frozen can be safe.

You can defrost food safely in the fridge, by using the microwave ‘defrost’ setting, or by placing it under cold running water. Once the food is thoroughly defrosted, it will spoil as quickly as fresh food, so be sure to cook it within a few hours.

Is it safe to refreeze food?

The answer to this is yes and no. Frozen meats and fish, once defrosted, shouldn’t be frozen again unless thoroughly cooked through. Once cooked, the majority of dangerous bacteria in the food will be destroyed, so it can be frozen again. Refreezing most other foods, such as bread, dairy, and vegetables, will cause it to degrade and become mostly inedible.

That’s everything you need to know! For more information on freezing and defrosting, we recommend taking a look at the FSA guidance notes here and here.